Attention-deficit/hyperactivity disorder: cognitive evoked potential (P300) topography predicts treatment response to methylphenidate

Objective: Auditory cognitive evoked potential (P300) topography predicts robust response to the stimulant pemoline in patients with attention-deficit/hyperactivity disorder (ADHD). Patients with a right fronto-central to parietal (FC2:P4) auditory P300 amplitude ratio >0.5 respond robustly to pemoline, whereas others do not. This study was performed to demonstrate whether the same test and ratio predict treatment response to methylphenidate. Methods: Patients aged 6–12 with DSM-IV diagnosis of ADHD were administered auditory and visual cognitive evoked potential (P300) testing. They then underwent single-blind treatment with an extended-release version of methylphenidate. Robust response was defined as a 60% decrease from baseline in a parent rated ADHD rating scale. Results: Nine of 20 subjects responded robustly. They did not differ from the non-robust responders in age, baseline attention or hyperactivity ratings, or any P300 parameter except auditory P300 topography. A FC2:P4 auditory P300 amplitude ratio >0.5 predicted robust response with a positive predictive value of 0.67 and a negative predictive value of 0.73. Conclusions: The ratio of right fronto-central to parietal auditory P300 amplitude predicts response to stimulants in patients with ADHD. As non-stimulant treatments are approved for the treatment of ADHD, tests such as this may help pinpoint whether to use a stimulant or a medicine with some other mechanism of action.